interface IPlayer {
    void tell(IColor pebble0, IEquation[] barter); 
    // the player is given a first pebble and is told about the equations

    void takeTurn(Card[] cc, ITurn t); 
    // the player is granted a turn and informed of current deck of cards
    
    void inform(String s); 
    // server informs player of something 

    // sequence contract: tell x { takeTurn | inform }*
}